In the USA both the 7-mg and 14-mg doses of Teriflunomide are licensed as both were shown to be effective. Outside the USA only the 14-mg dose is licensed.
However, the 14-mg dose was superior to the 7-mg dose on several outcomes in the phase 3 trials.
In general 7-mg is prescribed to MSers who can't tolerate the higher 14-mg dose. This may occur due to gastrointestinal symptoms or other blood abnormalities.
Outside the USA where the 7-mg tablet is not available you can take the 14-mg tablet alternate days. Splitting the tablet is not easy as it is not scored and doing so breaks the enteric coating.
The half-life of teriflunomide is very long so alternate day dosing is fine.